Event clustering for a network assurance platform

ABSTRACT

Systems, methods, and computer-readable media for clustering events occurring in a network environment for providing network assurance. In one embodiment, a system can identify event states of network events defined by values of parameters of a network environment. The system can determine a confidence score that at least one of the values of parameters is associated with a specific event state using the network events and the identified event states of the network events. The confidence score can be presented to a user for purposes of providing network assurance for the network environment.

The present technology pertains to network analytics, and morespecifically to clustering events in a network environment for providingnetwork assurance.

BACKGROUND

In a network environment, sensors can be placed at various devices orelements in the network to collect flow data and network statistics fromdifferent locations. The collected data from the sensors can be analyzedto monitor and troubleshoot the network. The data collected from thesensors can provide valuable details about the status, security, orperformance of the network, as well as any network elements. Informationabout the sensors can also help interpret the data from the sensors, inorder to infer or ascertain additional details from the collected data.For example, understanding the placement of a sensor relative to othersensors in the network can provide a context to the data reported by thesensors, which can further help identify specific patterns or conditionsin the network. As network environments increase in size and complexitya large amount of data is collected and generated in monitoring thenetwork environments. Unfortunately, larger amounts of data generatedfor network environments make it more difficult to analyze the data andsubsequently monitor network environments. Moreover, larger amounts ofdata generated for network environments make it more difficult toquickly and effectively diagnose problems in the network environments inproviding network assurance.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only exemplary embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the principlesherein are described and explained with additional specificity anddetail through the use of the accompanying drawings in which:

FIGS. 1A and 1B illustrate example network environments;

FIG. 2A illustrates an example object model for a network;

FIG. 2B illustrates an example object model for a tenant object in theexample object model from FIG. 2A;

FIG. 2C illustrates an example association of various objects in theexample object model from FIG. 2A;

FIG. 2D illustrates a schematic diagram of example models forimplementing the example object model from FIG. 2A;

FIG. 3A illustrates an example network assurance appliance;

FIG. 3B illustrates an example system for network assurance;

FIG. 3C illustrates a schematic diagram of an example system for staticpolicy analysis in a network, in accordance with various aspects of thesubject technology;

FIG. 4 illustrates an example method embodiment for network assurance;

FIG. 5 illustrates an example event clustering system;

FIG. 6 illustrates another example method embodiment for networkassurance;

FIG. 7 illustrates a diagram of an example logical flow for determiningconfidence scores for parameter values defining network events;

FIG. 8 illustrates an example network device in accordance with variousembodiments; and

FIG. 9 illustrates an example computing device in accordance withvarious embodiments.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various embodiments of the disclosure are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the disclosure.

Various embodiments of the disclosure are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the disclosure.Thus, the following description and drawings are illustrative and arenot to be construed as limiting. Numerous specific details are describedto provide a thorough understanding of the disclosure. However, incertain instances, well-known or conventional details are not describedin order to avoid obscuring the description. References to one or anembodiment in the present disclosure can be references to the sameembodiment or any embodiment; and, such references mean at least one ofthe embodiments.

Reference to “one embodiment” or “an embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the disclosure. Theappearances of the phrase “in one embodiment” in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. Moreover, various features are described which may beexhibited by some embodiments and not by others.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the disclosure, and in thespecific context where each term is used. Alternative language andsynonyms may be used for any one or more of the terms discussed herein,and no special significance should be placed upon whether or not a termis elaborated or discussed herein. In some cases, synonyms for certainterms are provided. A recital of one or more synonyms does not excludethe use of other synonyms. The use of examples anywhere in thisspecification including examples of any terms discussed herein isillustrative only, and is not intended to further limit the scope andmeaning of the disclosure or of any example term. Likewise, thedisclosure is not limited to various embodiments given in thisspecification.

Without intent to limit the scope of the disclosure, examples ofinstruments, apparatus, methods and their related results according tothe embodiments of the present disclosure are given below. Note thattitles or subtitles may be used in the examples for convenience of areader, which in no way should limit the scope of the disclosure. Unlessotherwise defined, technical and scientific terms used herein have themeaning as commonly understood by one of ordinary skill in the art towhich this disclosure pertains. In the case of conflict, the presentdocument, including definitions will control.

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be obvious from thedescription, or can be learned by practice of the herein disclosedprinciples. The features and advantages of the disclosure can berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures of the disclosure will become more fully apparent from thefollowing description and appended claims, or can be learned by thepractice of the principles set forth herein.

Overview

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be obvious from thedescription, or can be learned by practice of the herein disclosedprinciples. The features and advantages of the disclosure can berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures of the disclosure will become more fully apparent from thefollowing description and appended claims, or can be learned by thepractice of the principles set forth herein.

Disclosed herein are systems, methods, and computer-readable media forclustering events occurring in a network environment for providingnetwork assurance. A system can identify event states of network eventsoccurring in a network environment and defined by values of parametersof the network environment. A confidence score that at least one of thevalues of the parameters of the network environment is associated with aspecific event state of the event states can be determined using thenetwork events and the identified event states of the network events.The system can present the confidence score, an identification of thespecific event state, and an identification of the at least one of thevalues of the parameters of the network environment to a user.

Network events in a network environment can be sorted into one or moreevent groups based on values of parameters of the network environmentdefining the network events. Event states of the network events can bedetermined and used along with the network events sorted into the one ormore event groups to determine a confidence score that at least one ofthe values of the parameters of the network environment is associatedwith a specific event state. The determined confidence score, anidentification of the specific event state, and an identification of theat least one of the values of the parameters of the network environmentcan be presented to a user.

A system can determine whether at least one value of parameters of anetwork environment define a specific number of network events greaterthan or equal to a specific number of events identified by a minimumsupport. If the at least one value of the parameters of the networkenvironment defines a specific number of network events greater than orequal to the specific number of events identified by the minimumsupport, a confidence score for the at least one value of the parametersof the network environment can be determined. The confidence score canbe an indication that the at least one value of the parameters of thenetwork environment is associated with a specific event state of theevents states of the network events.

Description Of Example Embodiments

The disclosed technology addresses the need in the art for providingnetwork assurance. The present technology involves system, methods, andcomputer-readable media for providing network assurance. The presenttechnology will be described in the following disclosure as follows. Thediscussion begins with an introductory discussion of network assuranceand a description of example computing environments, as illustrated inFIGS. 1A and 1B. A discussion of network models for network assurance,as shown in FIGS. 2A through 2D, and network assurance systems andmethods, as shown in FIGS. 3A-C, 4, 5, and 6 will then follow. Thediscussion continues with a description and examples of determining aconfidence score for providing network assurance, as shown in FIG. 7.The discussion concludes with a description of an example networkdevice, as illustrated in FIG. 8, and an example computing device, asillustrated in FIG. 9, including example hardware components suitablefor hosting software applications and performing computing operations.The disclosure now turns to an introductory discussion of networkassurance.

Network assurance is the guarantee or determination that the network isbehaving as intended by the network operator and has been configuredproperly (e.g., the network is doing what it is intended to do). Intentcan encompass various network operations, such as bridging, routing,security, service chaining, endpoints, compliance, QoS (Quality ofService), audits, etc.

Intent can be embodied in one or more policies, settings,configurations, etc., defined for the network and individual networkelements (e.g., switches, routers, applications, resources, etc.).However, often times, the configurations, policies, etc., defined by anetwork operator are incorrect or not accurately reflected in the actualbehavior of the network. For example, a network operator specifies aconfiguration A for one or more types of traffic but later finds outthat the network is actually applying configuration B to that traffic orotherwise processing that traffic in a manner that is inconsistent withconfiguration A. This can be a result of many different causes, such ashardware errors, software bugs, varying priorities, configurationconflicts, misconfiguration of one or more settings, improper rulerendering by devices, unexpected errors or events, software upgrades,configuration changes, failures, etc. As another example, a networkoperator implements configuration C but one or more other configurationsresult in the network behaving in a manner that is inconsistent with theintent reflected by the implementation of configuration C. For example,such a situation can result when configuration C conflicts with otherconfigurations in the network.

The approaches herein can provide network assurance by modeling variousaspects of the network and/or performing consistency checks as well asother network assurance checks. The network assurance approaches hereincan be implemented in various types of networks, including a privatenetwork, such as a local area network (LAN); an enterprise network; astandalone or traditional network, such as a data center network; anetwork including a physical or underlay layer and a logical or overlaylayer, such as a VXLAN or software-defined network (SDN) (e.g.,Application Centric Infrastructure (ACI) or VMware NSX networks); etc.

Network models can be constructed for a network and implemented fornetwork assurance. A network model can provide a representation of oneor more aspects of a network, including, without limitation thenetwork's policies, configurations, requirements, security, routing,topology, applications, hardware, filters, contracts, access controllists, infrastructure, etc. As will be further explained below,different types of models can be generated for a network.

Such models can be implemented to ensure that the behavior of thenetwork will be consistent (or is consistent) with the intended behaviorreflected through specific configurations (e.g., policies, settings,definitions, etc.) implemented by the network operator. Unliketraditional network monitoring, which involves sending and analyzingdata packets and observing network behavior, network assurance can beperformed through modeling without necessarily ingesting packet data ormonitoring traffic or network behavior. This can result in foresight,insight, and hindsight: problems can be prevented before they occur,identified when they occur, and fixed immediately after they occur.

Thus, network assurance can involve modeling properties of the networkto deterministically predict the behavior of the network. The networkcan be determined to be healthy if the model(s) indicate proper behavior(e.g., no inconsistencies, conflicts, errors, etc.). The network can bedetermined to be functional, but not fully healthy, if the modelingindicates proper behavior but some inconsistencies. The network can bedetermined to be non-functional and not healthy if the modelingindicates improper behavior and errors. If inconsistencies or errors aredetected by the modeling, a detailed analysis of the correspondingmodel(s) can allow one or more underlying or root problems to beidentified with great accuracy.

The modeling can consume numerous types of smart events which model alarge amount of behavioral aspects of the network. Smart events canimpact various aspects of the network, such as underlay services,overlay services, tenant connectivity, tenant security, tenant endpoint(EP) mobility, tenant policy, tenant routing, resources, etc.

Having described various aspects of network assurance, the disclosurenow turns to a discussion of example network environments for networkassurance.

FIG. 1A illustrates a diagram of an example Network Environment 100,such as a data center. The Network Environment 100 can include a Fabric120 which can represent the physical layer or infrastructure (e.g.,underlay) of the Network Environment 100. Fabric 120 can include Spines102 (e.g., spine routers or switches) and Leafs 104 (e.g., leaf routersor switches) which can be interconnected for routing or switchingtraffic in the Fabric 120. Spines 102 can interconnect Leafs 104 in theFabric 120, and Leafs 104 can connect the Fabric 120 to an overlay orlogical portion of the Network Environment 100, which can includeapplication services, servers, virtual machines, containers, endpoints,etc. Thus, network connectivity in the Fabric 120 can flow from Spines102 to Leafs 104, and vice versa. The interconnections between Leafs 104and Spines 102 can be redundant (e.g., multiple interconnections) toavoid a failure in routing. In some embodiments, Leafs 104 and Spines102 can be fully connected, such that any given Leaf is connected toeach of the Spines 102, and any given Spine is connected to each of theLeafs 104. Leafs 104 can be, for example, top-of-rack (“ToR”) switches,aggregation switches, gateways, ingress and/or egress switches, provideredge devices, and/or any other type of routing or switching device.

Leafs 104 can be responsible for routing and/or bridging tenant orcustomer packets and applying network policies or rules. Networkpolicies and rules can be driven by one or more Controllers 116, and/orimplemented or enforced by one or more devices, such as Leafs 104. Leafs104 can connect other elements to the Fabric 120. For example, Leafs 104can connect Servers 106, Hypervisors 108, Virtual Machines (VMs) 110,Applications 112, Network Device 114, etc., with Fabric 120. Suchelements can reside in one or more logical or virtual layers ornetworks, such as an overlay network. In some cases, Leafs 104 canencapsulate and decapsulate packets to and from such elements (e.g.,Servers 106) in order to enable communications throughout NetworkEnvironment 100 and Fabric 120. Leafs 104 can also provide any otherdevices, services, tenants, or workloads with access to Fabric 120. Insome cases, Servers 106 connected to Leafs 104 can similarly encapsulateand decapsulate packets to and from Leafs 104. For example, Servers 106can include one or more virtual switches or routers or tunnel endpointsfor tunneling packets between an overlay or logical layer hosted by, orconnected to, Servers 106 and an underlay layer represented by Fabric120 and accessed via Leafs 104.

Applications 112 can include software applications, services,containers, appliances, functions, service chains, etc. For example,Applications 112 can include a firewall, a database, a CDN server, anIDS/IPS, a deep packet inspection service, a message router, a virtualswitch, etc. An application from Applications 112 can be distributed,chained, or hosted by multiple endpoints (e.g., Servers 106, VMs 110,etc.), or may run or execute entirely from a single endpoint.

VMs 110 can be virtual machines hosted by Hypervisors 108 or virtualmachine managers running on Servers 106. VMs 110 can include workloadsrunning on a guest operating system on a respective server. Hypervisors108 can provide a layer of software, firmware, and/or hardware thatcreates, manages, and/or runs the VMs 110. Hypervisors 108 can allow VMs110 to share hardware resources on Servers 106, and the hardwareresources on Servers 106 to appear as multiple, separate hardwareplatforms. Moreover, Hypervisors 108 on Servers 106 can host one or moreVMs 110.

In some cases, VMs 110 and/or Hypervisors 108 can be migrated to otherServers 106. Servers 106 can similarly be migrated to other locations inNetwork Environment 100. For example, a server connected to a specificleaf can be changed to connect to a different or additional leaf. Suchconfiguration or deployment changes can involve modifications tosettings, configurations and policies that are applied to the resourcesbeing migrated as well as other network components.

In some cases, one or more Servers 106, Hypervisors 108, and/or VMs 110can represent or reside in a tenant or customer space. Tenant space caninclude workloads, services, applications, devices, networks, and/orresources that are associated with one or more clients or subscribers.Accordingly, traffic in Network Environment 100 can be routed based onspecific tenant policies, spaces, agreements, configurations, etc.Moreover, addressing can vary between one or more tenants. In someconfigurations, tenant spaces can be divided into logical segmentsand/or networks and separated from logical segments and/or networksassociated with other tenants. Addressing, policy, security andconfiguration information between tenants can be managed by Controllers116, Servers 106, Leafs 104, etc.

Configurations in Network Environment 100 can be implemented at alogical level, a hardware level (e.g., physical), and/or both. Forexample, configurations can be implemented at a logical and/or hardwarelevel based on endpoint or resource attributes, such as endpoint typesand/or application groups or profiles, through a software-definednetwork (SDN) framework (e.g., Application-Centric Infrastructure (ACI)or VMWARE NSX). To illustrate, one or more administrators can defineconfigurations at a logical level (e.g., application or software level)through Controllers 116, which can implement or propagate suchconfigurations through Network Environment 100. In some examples,Controllers 116 can be Application Policy Infrastructure Controllers(APICs) in an ACI framework. In other examples, Controllers 116 can beone or more management components for associated with other SDNsolutions, such as NSX Managers.

Such configurations can define rules, policies, priorities, protocols,attributes, objects, etc., for routing and/or classifying traffic inNetwork Environment 100. For example, such configurations can defineattributes and objects for classifying and processing traffic based onEndpoint Groups (EPGs), Security Groups (SGs), VM types, bridge domains(BDs), virtual routing and forwarding instances (VRFs), tenants,priorities, firewall rules, etc. Other example network objects andconfigurations are further described below. Traffic policies and rulescan be enforced based on tags, attributes, or other characteristics ofthe traffic, such as protocols associated with the traffic, EPGsassociated with the traffic, SGs associated with the traffic, networkaddress information associated with the traffic, etc. Such policies andrules can be enforced by one or more elements in Network Environment100, such as Leafs 104, Servers 106, Hypervisors 108, Controllers 116,etc. As previously explained, Network Environment 100 can be configuredaccording to one or more particular software-defined network (SDN)solutions, such as CISCO ACI or VMWARE NSX. These example SDN solutionsare briefly described below.

ACI can provide an application-centric or policy-based solution throughscalable distributed enforcement. ACI supports integration of physicaland virtual environments under a declarative configuration model fornetworks, servers, services, security, requirements, etc. For example,the ACI framework implements EPGs, which can include a collection ofendpoints or applications that share common configuration requirements,such as security, QoS, services, etc. Endpoints can be virtual/logicalor physical devices, such as VMs, containers, hosts, or physical serversthat are connected to Network Environment 100. Endpoints can have one ormore attributes such as a VM name, guest OS name, a security tag,application profile, etc. Application configurations can be appliedbetween EPGs, instead of endpoints directly, in the form of contracts.Leafs 104 can classify incoming traffic into different EPGs. Theclassification can be based on, for example, a network segmentidentifier such as a VLAN ID, VXLAN Network Identifier (VNID), NVGREVirtual Subnet Identifier (VSID), MAC address, IP address, etc.

In some cases, classification in the ACI infrastructure can beimplemented by Application Virtual Switches (AVS), which can run on ahost, such as a server or switch. For example, an AVS can classifytraffic based on specified attributes, and tag packets of differentattribute EPGs with different identifiers, such as network segmentidentifiers (e.g., VLAN ID). Finally, Leafs 104 can tie packets withtheir attribute EPGs based on their identifiers and enforce policies,which can be implemented and/or managed by one or more Controllers 116.Leaf 104 can classify to which EPG the traffic from a host belongs andenforce policies accordingly.

Another example SDN solution is based on VMWARE NSX. With VMWARE NSX,hosts can run a distributed firewall (DFW) which can classify andprocess traffic. Consider a case where three types of VMs, namely,application, database and web VMs, are put into a single layer-2 networksegment. Traffic protection can be provided within the network segmentbased on the VM type. For example, HTTP traffic can be allowed among webVMs, and disallowed between a web VM and an application or database VM.To classify traffic and implement policies, VMWARE NSX can implementsecurity groups, which can be used to group the specific VMs (e.g., webVMs, application VMs, database VMs). DFW rules can be configured toimplement policies for the specific security groups. To illustrate, inthe context of the previous example, DFW rules can be configured toblock HTTP traffic between web, application, and database securitygroups.

Returning now to FIG. 1A, Network Environment 100 can deploy differenthosts via Leafs 104, Servers 106, Hypervisors 108, VMs 110, Applications112, and Controllers 116, such as VMWARE ESXi hosts, WINDOWS HYPER-Vhosts, bare metal physical hosts, etc. Network Environment 100 mayinteroperate with a variety of Hypervisors 108, Servers 106 (e.g.,physical and/or virtual servers), SDN orchestration platforms, etc.Network Environment 100 may implement a declarative model to allow itsintegration with application design and holistic network policy.

Controllers 116 can provide centralized access to fabric information,application configuration, resource configuration, application-levelconfiguration modeling for a software-defined network (SDN)infrastructure, integration with management systems or servers, etc.Controllers 116 can form a control plane that interfaces with anapplication plane via northbound APIs and a data plane via southboundAPIs.

As previously noted, Controllers 116 can define and manageapplication-level model(s) for configurations in Network Environment100. In some cases, application or device configurations can also bemanaged and/or defined by other components in the network. For example,a hypervisor or virtual appliance, such as a VM or container, can run aserver or management tool to manage software and services in NetworkEnvironment 100, including configurations and settings for virtualappliances.

As illustrated above, Network Environment 100 can include one or moredifferent types of SDN solutions, hosts, etc. For the sake of clarityand explanation purposes, various examples in the disclosure will bedescribed with reference to an ACI framework, and Controllers 116 may beinterchangeably referenced as controllers, APICs, or APIC controllers.However, it should be noted that the technologies and concepts hereinare not limited to ACI solutions and may be implemented in otherarchitectures and scenarios, including other SDN solutions as well asother types of networks which may not deploy an SDN solution.

Further, as referenced herein, the term “hosts” can refer to Servers 106(e.g., physical or logical), Hypervisors 108, VMs 110, containers (e.g.,Applications 112), etc., and can run or include any type of server orapplication solution. Non-limiting examples of “hosts” can includevirtual switches or routers, such as distributed virtual switches (DVS),application virtual switches (AVS), vector packet processing (VPP)switches; VCENTER and NSX MANAGERS; bare metal physical hosts; HYPER-Vhosts; VMs; DOCKER Containers; etc.

FIG. 1B illustrates another example of Network Environment 100. In thisexample, Network Environment 100 includes Endpoints 122 connected toLeafs 104 in Fabric 120. Endpoints 122 can be physical and/or logical orvirtual entities, such as servers, clients, VMs, hypervisors, softwarecontainers, applications, resources, network devices, workloads, etc.For example, an Endpoint 122 can be an object that represents a physicaldevice (e.g., server, client, switch, etc.), an application (e.g., webapplication, database application, etc.), a logical or virtual resource(e.g., a virtual switch, a virtual service appliance, a virtualizednetwork function (VNF), a VM, a service chain, etc.), a containerrunning a software resource (e.g., an application, an appliance, a VNF,a service chain, etc.), storage, a workload or workload engine, etc.Endpoints 122 can have an address (e.g., an identity), a location (e.g.,host, network segment, virtual routing and forwarding (VRF) instance,domain, etc.), one or more attributes (e.g., name, type, version, patchlevel, OS name, OS type, etc.), a tag (e.g., security tag), a profile,etc.

Endpoints 122 can be associated with respective Logical Groups 118.Logical Groups 118 can be logical entities containing endpoints(physical and/or logical or virtual) grouped together according to oneor more attributes, such as endpoint type (e.g., VM type, workload type,application type, etc.), one or more requirements (e.g., policyrequirements, security requirements, QoS requirements, customerrequirements, resource requirements, etc.), a resource name (e.g., VMname, application name, etc.), a profile, platform or operating system(OS) characteristics (e.g., OS type or name including guest and/or hostOS, etc.), an associated network or tenant, one or more policies, a tag,etc. For example, a logical group can be an object representing acollection of endpoints grouped together. To illustrate, Logical Group 1can contain client endpoints, Logical Group 2 can contain web serverendpoints, Logical Group 3 can contain application server endpoints,Logical Group N can contain database server endpoints, etc. In someexamples, Logical Groups 118 are EPGs in an ACI environment and/or otherlogical groups (e.g., SGs) in another SDN environment.

Traffic to and/or from Endpoints 122 can be classified, processed,managed, etc., based Logical Groups 118. For example, Logical Groups 118can be used to classify traffic to or from Endpoints 122, apply policiesto traffic to or from Endpoints 122, define relationships betweenEndpoints 122, define roles of Endpoints 122 (e.g., whether an endpointconsumes or provides a service, etc.), apply rules to traffic to or fromEndpoints 122, apply filters or access control lists (ACLs) to trafficto or from Endpoints 122, define communication paths for traffic to orfrom Endpoints 122, enforce requirements associated with Endpoints 122,implement security and other configurations associated with Endpoints122, etc.

In an ACI environment, Logical Groups 118 can be EPGs used to definecontracts in the ACI. Contracts can include rules specifying what andhow communications between EPGs take place. For example, a contract candefine what provides a service, what consumes a service, and what policyobjects are related to that consumption relationship. A contract caninclude a policy that defines the communication path and all relatedelements of a communication or relationship between endpoints or EPGs.For example, a Web EPG can provide a service that a Client EPG consumes,and that consumption can be subject to a filter (ACL) and a servicegraph that includes one or more services, such as firewall inspectionservices and server load balancing.

FIG. 2A illustrates a diagram of an example Management Information Model200 for an SDN network, such as Network Environment 100. The followingdiscussion of Management Information Model 200 references various termswhich shall also be used throughout the disclosure. Accordingly, forclarity, the disclosure shall first provide below a list of terminology,which will be followed by a more detailed discussion of ManagementInformation Model 200.

As used herein, an “Alias” can refer to a changeable name for a givenobject. Thus, even if the name of an object, once created, cannot bechanged, the Alias can be a field that can be changed.

As used herein, the term “Aliasing” can refer to a rule (e.g.,contracts, policies, configurations, etc.) that overlaps one or moreother rules. For example, Contract 1 defined in a logical model of anetwork can be said to be aliasing Contract 2 defined in the logicalmodel of the network if Contract 1 overlaps Contract 1. In this example,by aliasing Contract 2, Contract 1 may render Contract 2 redundant orinoperable. For example, if Contract 1 has a higher priority thanContract 2, such aliasing can render Contract 2 redundant based onContract 1's overlapping and higher priority characteristics.

As used herein, the term “APIC” can refer to one or more controllers(e.g., Controllers 116) in an ACI framework. The APIC can provide aunified point of automation and management, policy programming,application deployment, health monitoring for an ACI multitenant fabric.The APIC can be implemented as a single controller, a distributedcontroller, or a replicated, synchronized, and/or clustered controller.

As used herein, the term “BDD” can refer to a binary decision tree. Abinary decision tree can be a data structure representing functions,such as Boolean functions.

As used herein, the term “BD” can refer to a bridge domain. A bridgedomain can be a set of logical ports that share the same flooding orbroadcast characteristics. Like a virtual LAN (VLAN), bridge domains canspan multiple devices. A bridge domain can be a L2 (Layer 2) construct.

As used herein, a “Consumer” can refer to an endpoint, resource, and/orEPG that consumes a service.

As used herein, a “Context” can refer to an L3 (Layer 3) address domainthat allows multiple instances of a routing table to exist and worksimultaneously. This increases functionality by allowing network pathsto be segmented without using multiple devices. Non-limiting examples ofa context or L3 address domain can include a Virtual Routing andForwarding (VRF) instance, a private network, and so forth.

As used herein, the term “Contract” can refer to rules or configurationsthat specify what and how communications in a network are conducted(e.g., allowed, denied, filtered, processed, etc.). In an ACI network,contracts can specify how communications between endpoints and/or EPGstake place. In some examples, a contract can provide rules andconfigurations akin to an Access Control List (ACL).

As used herein, the term “Distinguished Name” (DN) can refer to a uniquename that describes an object, such as an MO, and locates its place inManagement Information Model 200. In some cases, the DN can be (orequate to) a Fully Qualified Domain Name (FQDN).

As used herein, the term “Endpoint Group” (EPG) can refer to a logicalentity or object associated with a collection or group of endoints aspreviously described with reference to FIG. 1B.

As used herein, the term “Filter” can refer to a parameter orconfiguration for allowing communications. For example, in a whitelistmodel where all communications are blocked by default, a communicationmust be given explicit permission to prevent such communication frombeing blocked. A filter can define permission(s) for one or morecommunications or packets. A filter can thus function similar to an ACLor Firewall rule. In some examples, a filter can be implemented in apacket (e.g., TCP/IP) header field, such as L3 protocol type, L4 (Layer4) ports, and so on, which is used to allow inbound or outboundcommunications between endpoints or EPGs, for example.

As used herein, the term “L2 Out” can refer to a bridged connection. Abridged connection can connect two or more segments of the same networkso that they can communicate. In an ACI framework, an L2 out can be abridged (Layer 2) connection between an ACI fabric (e.g., Fabric 120)and an outside Layer 2 network, such as a switch.

As used herein, the term “3 Out” can refer to a routed connection. Arouted Layer 3 connection uses a set of protocols that determine thepath that data follows in order to travel across networks from itssource to its destination. Routed connections can perform forwarding(e.g., IP forwarding) according to a protocol selected, such as BGP(border gateway protocol), OSPF (Open Shortest Path First), EIGRP(Enhanced Interior Gateway Routing Protocol), etc.

As used herein, the term “Managed Object” (MO) can refer to an abstractrepresentation of objects that are managed in a network (e.g., NetworkEnvironment 100). The objects can be concrete objects (e.g., a switch,server, adapter, etc.), or logical objects (e.g., an applicationprofile, an EPG, a fault, etc.). The MOs can be network resources orelements that are managed in the network. For example, in an ACIenvironment, an MO can include an abstraction of an ACI fabric (e.g.,Fabric 120) resource.

As used herein, the term “Management Information Tree” (MIT) can referto a hierarchical management information tree containing the MOs of asystem. For example, in ACI, the MIT contains the MOs of the ACI fabric(e.g., Fabric 120). The MIT can also be referred to as a ManagementInformation Model (MIM), such as Management Information Model 200.

As used herein, the term “Policy” can refer to one or morespecifications for controlling some aspect of system or networkbehavior. For example, a policy can include a named entity that containsspecifications for controlling some aspect of system behavior. Toillustrate, a Layer 3 Outside Network Policy can contain the BGPprotocol to enable BGP routing functions when connecting Fabric 120 toan outside Layer 3 network.

As used herein, the term “Profile” can refer to the configurationdetails associated with a policy. For example, a profile can include anamed entity that contains the configuration details for implementingone or more instances of a policy. To illustrate, a switch node profilefor a routing policy can contain the switch-specific configurationdetails to implement the BGP routing protocol.

As used herein, the term “Provider” refers to an object or entityproviding a service. For example, a provider can be an EPG that providesa service.

As used herein, the term “Subject” refers to one or more parameters in acontract for defining communications. For example, in ACI, subjects in acontract can specify what information can be communicated and how.Subjects can function similar to ACLs.

As used herein, the term “Tenant” refers to a unit of isolation in anetwork. For example, a tenant can be a secure and exclusive virtualcomputing environment. In ACI, a tenant can be a unit of isolation froma policy perspective, but does not necessarily represent a privatenetwork. Indeed, ACI tenants can contain multiple private networks(e.g., VRFs). Tenants can represent a customer in a service providersetting, an organization or domain in an enterprise setting, or just agrouping of policies.

As used herein, the term “VRF” refers to a virtual routing andforwarding instance. The VRF can define a Layer 3 address domain thatallows multiple instances of a routing table to exist and worksimultaneously. This increases functionality by allowing network pathsto be segmented without using multiple devices. Also known as a contextor private network.

Having described various terms used herein, the disclosure now returnsto a discussion of Management Information Model (MIM) 200 in FIG. 2A. Aspreviously noted, MIM 200 can be a hierarchical management informationtree or MIT. Moreover, MIM 200 can be managed and processed byControllers 116, such as APICs in an ACI. Controllers 116 can enable thecontrol of managed resources by presenting their manageablecharacteristics as object properties that can be inherited according tothe location of the object within the hierarchical structure of themodel.

The hierarchical structure of MIM 200 starts with Policy Universe 202 atthe top (Root) and contains parent and child nodes 116, 204, 206, 208,210, 212. Nodes 116, 202, 204, 206, 208, 210, 212 in the tree representthe managed objects (MOs) or groups of objects. Each object in thefabric (e.g., Fabric 120) has a unique distinguished name (DN) thatdescribes the object and locates its place in the tree. The Nodes 116,202, 204, 206, 208, 210, 212 can include the various MOs, as describedbelow, which contain policies that govern the operation of the system.

Controllers 116

Controllers 116 (e.g., APIC controllers) can provide management, policyprogramming, application deployment, and health monitoring for Fabric120.

Node 204

Node 204 includes a tenant container for policies that enable anadministrator to exercise domain-based access control. Non-limitingexamples of tenants can include:

User tenants defined by the administrator according to the needs ofusers. They contain policies that govern the operation of resources suchas applications, databases, web servers, network-attached storage,virtual machines, and so on.

The common tenant is provided by the system but can be configured by theadministrator. It contains policies that govern the operation ofresources accessible to all tenants, such as firewalls, load balancers,Layer 4 to Layer 7 services, intrusion detection appliances, and so on.

The infrastructure tenant is provided by the system but can beconfigured by the administrator. It contains policies that govern theoperation of infrastructure resources such as the fabric overlay (e.g.,VXLAN). It also enables a fabric provider to selectively deployresources to one or more user tenants. Infrastructure tenant polices canbe configurable by the administrator.

The management tenant is provided by the system but can be configured bythe administrator. It contains policies that govern the operation offabric management functions used for in-band and out-of-bandconfiguration of fabric nodes. The management tenant contains a privateout-of-bound address space for the Controller/Fabric internalcommunications that is outside the fabric data path that provides accessthrough the management port of the switches. The management tenantenables discovery and automation of communications with virtual machinecontrollers.

Node 206

Node 206 can contain access policies that govern the operation of switchaccess ports that provide connectivity to resources such as storage,compute, Layer 2 and Layer 3 (bridged and routed) connectivity, virtualmachine hypervisors, Layer 4 to Layer 7 devices, and so on. If a tenantrequires interface configurations other than those provided in thedefault link, Cisco Discovery Protocol (CDP), Link Layer DiscoveryProtocol (LLDP), Link Aggregation Control Protocol (LACP), or SpanningTree Protocol (STP), an administrator can configure access policies toenable such configurations on the access ports of Leafs 104.

Node 206 can contain fabric policies that govern the operation of theswitch fabric ports, including such functions as Network Time Protocol(NTP) server synchronization, Intermediate System-to-Intermediate SystemProtocol (IS-IS), Border Gateway Protocol (BGP) route reflectors, DomainName System (DNS) and so on. The fabric MO contains objects such aspower supplies, fans, chassis, and so on.

Node 208

Node 208 can contain VM domains that group VM controllers with similarnetworking policy requirements. VM controllers can share virtual space(e.g., VLAN or VXLAN space) and application EPGs. Controllers 116communicate with the VM controller to publish network configurationssuch as port groups that are then applied to the virtual workloads.

Node 210

Node 210 can contain Layer 4 to Layer 7 service integration life cycleautomation framework that enables the system to dynamically respond whena service comes online or goes offline. Policies can provide servicedevice package and inventory management functions.

Node 212

Node 212 can contain access, authentication, and accounting (AAA)policies that govern user privileges, roles, and security domains ofFabric 120.

The hierarchical policy model can fit well with an API, such as a RESTAPI interface. When invoked, the API can read from or write to objectsin the MIT. URLs can map directly into distinguished names that identifyobjects in the MIT. Data in the MIT can be described as a self-containedstructured tree text document encoded in XML or JSON, for example.

FIG. 2B illustrates an example object model 220 for a tenant portion ofMIM 200. As previously noted, a tenant is a logical container forapplication policies that enable an administrator to exercisedomain-based access control. A tenant thus represents a unit ofisolation from a policy perspective, but it does not necessarilyrepresent a private network. Tenants can represent a customer in aservice provider setting, an organization or domain in an enterprisesetting, or just a convenient grouping of policies. Moreover, tenantscan be isolated from one another or can share resources.

Tenant portion 204A of MIM 200 can include various entities, and theentities in Tenant Portion 204A can inherit policies from parententities. Non-limiting examples of entities in Tenant Portion 204A caninclude Filters 240, Contracts 236, Outside Networks 222, Bridge Domains230, VRF Instances 234, and Application Profiles 224.

Bridge Domains 230 can include Subnets 232. Contracts 236 can includeSubjects 238. Application Profiles 224 can contain one or more EPGs 226.Some applications can contain multiple components. For example, ane-commerce application could require a web server, a database server,data located in a storage area network, and access to outside resourcesthat enable financial transactions. Application Profile 224 contains asmany (or as few) EPGs as necessary that are logically related toproviding the capabilities of an application.

EPG 226 can be organized in various ways, such as based on theapplication they provide, the function they provide (such asinfrastructure), where they are in the structure of the data center(such as DMZ), or whatever organizing principle that a fabric or tenantadministrator chooses to use.

EPGs in the fabric can contain various types of EPGs, such asapplication EPGs, Layer 2 external outside network instance EPGs, Layer3 external outside network instance EPGs, management EPGs forout-of-band or in-band access, etc. EPGs 226 can also contain Attributes228, such as encapsulation-based EPGs, IP-based EPGs, or MAC-based EPGs.

As previously mentioned, EPGs can contain endpoints (e.g., EPs 122) thathave common characteristics or attributes, such as common policyrequirements (e.g., security, virtual machine mobility (VMM), QoS, orLayer 4 to Layer 7 services). Rather than configure and manage endpointsindividually, they can be placed in an EPG and managed as a group.

Policies apply to EPGs, including the endpoints they contain. An EPG canbe statically configured by an administrator in Controllers 116, ordynamically configured by an automated system such as VCENTER orOPENSTACK.

To activate tenant policies in Tenant Portion 204A, fabric accesspolicies should be configured and associated with tenant policies.Access policies enable an administrator to configure other networkconfigurations, such as port channels and virtual port channels,protocols such as LLDP, CDP, or LACP, and features such as monitoring ordiagnostics.

FIG. 2C illustrates an example Association 260 of tenant entities andaccess entities in MIM 200. Policy Universe 202 contains Tenant Portion204A and Access Portion 206A. Thus, Tenant Portion 204A and AccessPortion 206A are associated through Policy Universe 202.

Access Portion 206A can contain fabric and infrastructure accesspolicies. Typically, in a policy model, EPGs are coupled with VLANs. Fortraffic to flow, an EPG is deployed on a leaf port with a VLAN in aphysical, VMM, L2 out, L3 out, or Fiber Channel domain, for example.

Access Portion 206A thus contains Domain Profile 236 which can define aphysical, VMM, L2 out, L3 out, or Fiber Channel domain, for example, tobe associated to the EPGs. Domain Profile 236 contains VLAN InstanceProfile 238 (e.g., VLAN pool) and Attacheable Access Entity Profile(AEP) 240, which are associated directly with application EPGs. The AEP240 deploys the associated application EPGs to the ports to which it isattached, and automates the task of assigning VLANs. While a large datacenter can have thousands of active VMs provisioned on hundreds ofVLANs, Fabric 120 can automatically assign VLAN IDs from VLAN pools.This saves time compared with trunking down VLANs in a traditional datacenter.

FIG. 2D illustrates a schematic diagram of example models forimplementing MIM 200. The network assurance models can include L_Model270A (Logical Model), LR_Model 270B (Logical Rendered Model or LogicalRuntime Model), Li_Model 272 (Logical Model for i), Ci_Model 274(Concrete model for i), and Hi_Model 276 (Hardware model or TCAM Modelfor i).

L_Model 270A is the logical representation of the objects and theirrelationships in MIM 200. L_Model 270A can be generated by Controllers116 based on configurations entered in Controllers 116 for the network,and thus represents the configurations of the network at Controllers116. This is the declaration of the “end-state” expression that isdesired when the elements of the network entities (e.g., applications)are connected and Fabric 120 is provisioned by Controllers 116. In otherwords, because L_Model 270A represents the configurations entered inControllers 116, including the objects and relationships in MIM 200, itcan also reflect the “intent” of the administrator: how theadministrator wants the network and network elements to behave.

LR_Model 270B is the abstract model expression that Controllers 116(e.g., APICs in ACI) resolve from L_Model 270A. LR_Model 270B can thusprovide the elemental configuration components that would be deliveredto the physical infrastructure (e.g., Fabric 120) to execute one or morepolicies. For example, LR_Model 270B can be delivered to Leafs 104 inFabric 120 to configure Leafs 104 for communication with attachedEndpoints 122.

Li_Model 272 is a switch-level or switch-specific model obtained fromLogical Model 270A and/or Resolved Model 270B. For example, Li_Model 272can represent the portion of L_Model 270A and/or LR_Model 270Bpertaining to a specific switch or router i. To illustrate, Li_Model 272L₁ can represent the portion of L_Model 270A and/or LR_Model 270Bpertaining to Leaf 1 (104). Thus, Li_Model 272 can be generated fromL_Model 270A and/or LR_Model 270B for one or more switch or routers(e.g., Leafs 104 and/or Spines 102) on Fabric 120.

Ci_Model 274 is the actual in-state configuration at the individualfabric member i (e.g., switch i). In other words, Ci_Model 274 is aswitch-level or switch-specific model that is based on Li_Model 272. Forexample, Controllers 116 can deliver Li_Model 272 to Leaf 1 (104). Leaf1 (104) can take Li_Model 272, which can be specific to Leaf 1 (104),and render the policies in Li_Model 272 into a concrete model, Ci_Model274, that runs on Leaf 1 (104). Leaf 1 (104) can render Li_Model 272 viathe OS on Leaf 1 (104), for example. Thus, Ci_Model 274 can be analogousto compiled software, as it is the form of Li_Model 272 that the switchOS at Leaf 1 (104) can execute.

Hi_Model 276 is also a switch-level or switch-specific model for switchi, but is based on Ci_Model 274 for switch i. Hi_Model 276 is the actualconfiguration (e.g., rules) stored or rendered on the hardware or memory(e.g., TCAM memory) at the individual fabric member i (e.g., switch i).For example, Hi_Model 276 can represent the configurations (e.g., rules)which Leaf 1 (104) stores or renders on the hardware (e.g., TCAM memory)of Leaf 1 (104) based on Ci_Model 274 at Leaf 1 (104). The switch OS atLeaf 1 (104) can render or execute Ci_Model 274, and Leaf 1 (104) canstore or render the configurations from Ci Model in storage, such as thememory or TCAM at Leaf 1 (104). The configurations from Hi_Model 276stored or rendered by Leaf 1 (104) represent the configurations thatwill be implemented by Leaf 1 (104) when processing traffic.

While Models 272, 274, 276 are shown as device-specific models, similarmodels can be generated or aggregated for a collection of fabric members(e.g., Leafs 104 and/or Spines 102) in Fabric 120. When combined,device-specific models, such as Model 272, Model 274, and/or Model 276,can provide a representation of Fabric 120 that extends beyond aparticular device. For example, in some cases, Li_Model 272, Ci Model272, and/or Hi Model 272 associated with some or all individual fabricmembers (e.g., Leafs 104 and Spines 102) can be combined or aggregatedto generate one or more aggregated models based on the individual fabricmembers.

As referenced herein, the terms H Model, T Model, and TCAM Model can beused interchangeably to refer to a hardware model, such as Hi_Model 276.For example, Ti Model, Hi Model and TCAMi Model may be usedinterchangeably to refer to Hi_Model 276.

Models 270A, 270B, 272, 274, 276 can provide representations of variousaspects of the network or various configuration stages for MIM 200. Forexample, one or more of Models 270A, 270B, 272, 274, 276 can be used togenerate Underlay Model 278 representing one or more aspects of Fabric120 (e.g., underlay topology, routing, etc.), Overlay Model 280representing one or more aspects of the overlay or logical segment(s) ofNetwork Environment 100 (e.g., COOP, MPBGP, tenants, VRFs, VLANs,VXLANs, virtual applications, VMs, hypervisors, virtual switching,etc.), Tenant Model 282 representing one or more aspects of Tenantportion 204A in MIM 200 (e.g., security, forwarding, service chaining,QoS, VRFs, BDs, Contracts, Filters, EPGs, subnets, etc.), ResourcesModel 284 representing one or more resources in Network Environment 100(e.g., storage, computing, VMs, port channels, physical elements, etc.),etc.

In general, L_Model 270A can be the high-level expression of what existsin the LR_Model 270B, which should be present on the concrete devices asCi_Model 274 and Hi_Model 276 expression. If there is any gap betweenthe models, there may be inconsistent configurations or problems.

FIG. 3A illustrates a diagram of an example Assurance Appliance 300 fornetwork assurance. In this example, Assurance Appliance 300 can includek VMs 110 operating in cluster mode. VMs are used in this example forexplanation purposes. However, it should be understood that otherconfigurations are also contemplated herein, such as use of containers,bare metal devices, Endpoints 122, or any other physical or logicalsystems. Moreover, while FIG. 3A illustrates a cluster modeconfiguration, other configurations are also contemplated herein, suchas a single mode configuration (e.g., single VM, container, or server)or a service chain for example.

Assurance Appliance 300 can run on one or more Servers 106, VMs 110,Hypervisors 108, EPs 122, Leafs 104, Controllers 116, or any othersystem or resource. For example, Assurance Appliance 300 can be alogical service or application running on one or more VMs 110 in NetworkEnvironment 100.

The Assurance Appliance 300 can include Data Framework 308, which can bebased on, for example, APACHE APEX and HADOOP. In some cases, assurancechecks can be written as individual operators that reside in DataFramework 308. This enables a natively horizontal scale-out architecturethat can scale to arbitrary number of switches in Fabric 120 (e.g., ACIfabric).

Assurance Appliance 300 can poll Fabric 120 at a configurableperiodicity (e.g., an epoch). The analysis workflow can be setup as aDAG (Directed Acyclic Graph) of Operators 310, where data flows from oneoperator to another and eventually results are generated and persistedto Database 302 for each interval (e.g., each epoch).

The north-tier implements API Server (e.g., APACHE Tomcat and Springframework) 304 and Web Server 306. A graphical user interface (GUI)interacts via the APIs exposed to the customer. These APIs can also beused by the customer to collect data from Assurance Appliance 300 forfurther integration into other tools.

Operators 310 in Data Framework 308 (e.g., APEX/Hadoop) can togethersupport assurance operations. Below are non-limiting examples ofassurance operations that can be performed by Assurance Appliance 300via Operators 310.

Security Policy Adherence

Assurance Appliance 300 can check to make sure the configurations orspecification from L_Model 270A, which may reflect the user's intent forthe network, including for example the security policies andcustomer-configured contracts, are correctly implemented and/or renderedin Li_Model 272, Ci_Model 274, and Hi_Model 276, and thus properlyimplemented and rendered by the fabric members (e.g., Leafs 104), andreport any errors, contract violations, or irregularities found.

Static Policy Analysis

Assurance Appliance 300 can check for issues in the specification of theuser's intent or intents (e.g., identify contradictory or conflictingpolicies in L_Model 270A).

TCAM Utilization

TCAM is a scarce resource in the fabric (e.g., Fabric 120). However,Assurance Appliance 300 can analyze the TCAM utilization by the networkdata (e.g., Longest Prefix Match (LPM) tables, routing tables, VLANtables, BGP updates, etc.), Contracts, Logical Groups 118 (e.g., EPGs),Tenants, Spines 102, Leafs 104, and other dimensions in NetworkEnvironment 100 and/or objects in MIM 200, to provide a network operatoror user visibility into the utilization of this scarce resource. Thiscan greatly help for planning and other optimization purposes.

Endpoint Checks

Assurance Appliance 300 can validate that the fabric (e.g. fabric 120)has no inconsistencies in the Endpoint information registered (e.g., twoleafs announcing the same endpoint, duplicate subnets, etc.), amongother such checks.

Tenant Routing Checks

Assurance Appliance 300 can validate that BDs, VRFs, subnets (bothinternal and external), VLANs, contracts, filters, applications, EPGs,etc., are correctly programmed.

Infrastructure Routing

Assurance Appliance 300 can validate that infrastructure routing (e.g.,IS-IS protocol) has no convergence issues leading to black holes, loops,flaps, and other problems.

MP-BGP Route Reflection Checks

The network fabric (e.g., Fabric 120) can interface with other externalnetworks and provide connectivity to them via one or more protocols,such as Border Gateway Protocol (BGP), Open Shortest Path First (OSPF),etc. The learned routes are advertised within the network fabric via,for example, MP-BGP. These checks can ensure that a route reflectionservice via, for example, MP-BGP (e.g., from Border Leaf) does not havehealth issues.

Logical Lint and Real-time Change Analysis

Assurance Appliance 300 can validate rules in the specification of thenetwork (e.g., L_Model 270A) are complete and do not haveinconsistencies or other problems. MOs in the MIM 200 can be checked byAssurance Appliance 300 through syntactic and semantic checks performedon L_Model 270A and/or the associated configurations of the MOs in MIM200. Assurance Appliance 300 can also verify that unnecessary, stale,unused or redundant configurations, such as contracts, are removed.

FIG. 3B illustrates an architectural diagram of an example system 350for network assurance. In some cases, system 350 can correspond to theDAG of Operators 310 previously discussed with respect to FIG. 3A Inthis example, Topology Explorer 312 communicates with Controllers 116(e.g., APIC controllers) in order to discover or otherwise construct acomprehensive topological view of Fabric 120 (e.g., Spines 102, Leafs104, Controllers 116, Endpoints 122, and any other components as well astheir interconnections). While various architectural components arerepresented in a singular, boxed fashion, it is understood that a givenarchitectural component, such as Topology Explorer 312, can correspondto one or more individual Operators 310 and may include one or morenodes or endpoints, such as one or more servers, VMs, containers,applications, service functions (e.g., functions in a service chain orvirtualized network function), etc.

Topology Explorer 312 is configured to discover nodes in Fabric 120,such as Controllers 116, Leafs 104, Spines 102, etc. Topology Explorer312 can additionally detect a majority election performed amongstControllers 116, and determine whether a quorum exists amongstControllers 116. If no quorum or majority exists, Topology Explorer 312can trigger an event and alert a user that a configuration or othererror exists amongst Controllers 116 that is preventing a quorum ormajority from being reached. Topology Explorer 312 can detect Leafs 104and Spines 102 that are part of Fabric 120 and publish theircorresponding out-of-band management network addresses (e.g., IPaddresses) to downstream services. This can be part of the topologicalview that is published to the downstream services at the conclusion ofTopology Explorer's 312 discovery epoch (e.g., 5 minutes, or some otherspecified interval).

Unified Collector 314 can receive the topological view from TopologyExplorer 312 and use the topology information to collect information fornetwork assurance from Fabric 120. Such information can include L_Model270A and/or LR_Model 270B from Controllers 116, switch softwareconfigurations (e.g., Ci_Model 274) from Leafs 104 and/or Spines 102,hardware configurations (e.g., Hi_Model 276) from Leafs 104 and/orSpines 102, etc. Unified Collector 314 can collect Ci_Model 274 andHi_Model 276 from individual fabric members (e.g., Leafs 104 and Spines102).

Unified Collector 314 can poll the devices that Topology Explorer 312discovers in order to collect data from Fabric 120 (e.g., from theconstituent members of the fabric).Unified Collector 314 can collect thedata using interfaces exposed by Controller 116 and/or switch software(e.g., switch OS), including, for example, a Representation StateTransfer (REST) Interface and a Secure Shell (SSH) Interface.

In some cases, Unified Collector 314 collects L_Model 270A, LR_Model270B, and/or Ci_Model 274 via a REST API, and the hardware information(e.g., configurations, tables, fabric card information, rules, routes,etc.) via SSH using utilities provided by the switch software, such asvirtual shell (VSH or VSHELL) for accessing the switch command-lineinterface (CLI) or VSH_LC shell for accessing runtime state of the linecard.

Unified Collector 314 can poll other information from Controllers 116,including: topology information, tenant forwarding/routing information,tenant security policies, contracts, interface policies, physical domainor VMM domain information, OOB (out-of-band) management IP's of nodes inthe fabric, etc.

Unified Collector 314 can also poll other information from Leafs 104 andSpines 102, such as: Ci Models 274 for VLANs, BDs, security policies,Link Layer Discovery Protocol (LLDP) connectivity information of Leafs104 and/or Spines 102, endpoint information from EPM/COOP, fabric cardinformation from Spines 102, routing information base (RIB) tables,forwarding information base (FIB) tables from Leafs 104 and/or Spines102, security group hardware tables (e.g., TCAM tables) from switches,etc.

Assurance Appliance 300 can run one or more instances of UnifiedCollector 314. For example, Assurance Appliance 300 can run one, two,three, or more instances of Unified Collector 314. The task of datacollecting for each node in the topology (e.g., Fabric 120 includingSpines 102, Leafs 104, Controllers 116, etc.) can be sharded or loadbalanced, to a unique instance of Unified Collector 314. Data collectionacross the nodes can thus be performed in parallel by one or moreinstances of Unified Collector 314. Within a given node, commands anddata collection can be executed serially. Assurance Appliance 300 cancontrol the number of threads used by each instance of Unified Collector314 to poll data from Fabric 120.

Data collected by Unified Collector 314 can be compressed and sent todownstream services. In some examples, Unified Collector 314 can collectdata in an online fashion or real-time fashion, and send the datadownstream, as it is collected, for further analysis. In some examples,Unified Collector 314 can collect data in an offline fashion, andcompile the data for later analysis or transmission.

Assurance Appliance 300 can contact Controllers 116, Spines 102, Leafs104, and other nodes to collect various types of data. In somescenarios, Assurance Appliance 300 may experience a failure (e.g.,connectivity problem, hardware or software error, etc.) that prevents itfrom being able to collect data for a period of time. AssuranceAppliance 300 can handle such failures seamlessly, and generate eventsbased on such failures.

Switch Logical Policy Generator 316 can receive L_Model 270A and/orLR_Model 270B from Unified Collector 314 and calculate Li_Model 272 foreach network device i (e.g., switch i) in Fabric 120. For example,Switch Logical Policy Generator 316 can receive L_Model 270A and/orLR_Model 270B and generate Li_Model 272 by projecting a logical modelfor each individual node i (e.g., Spines 102 and/or Leafs 104) in Fabric120. Switch Logical Policy Generator 316 can generate Li_Model 272 foreach switch in Fabric 120, thus creating a switch logical model based onL_Model 270A for each switch.

Switch Logical Configuration Generator 316 can also perform changeanalysis and generate lint events or records for problems discovered inL_Model 270A and/or LR_Model 270B. The lint events or records can beused to generate alerts for a user or network operator.

Policy Operator 318 can receive Ci_Model 274 and Hi_Model 276 for eachswitch from Unified Collector 314, and Li_Model 272 for each switch fromSwitch Logical Policy Generator 316, and perform assurance checks andanalysis (e.g., security adherence checks, TCAM utilization analysis,etc.) based on Ci_Model 274, Hi_Model 276, and Li_Model 272. PolicyOperator 318 can perform assurance checks on a switch-by-switch basis bycomparing one or more of the models.

Returning to Unified Collector 314, Unified Collector 314 can also sendL_Model 270A and/or LR_Model 270B to Routing Policy Parser 320, andCi_Model 274 and Hi_Model 276 to Routing Parser 326.

Routing Policy Parser 320 can receive L_Model 270A and/or LR_Model 270Band parse the model(s) for information that may be relevant todownstream operators, such as Endpoint Checker 322 and Tenant RoutingChecker 324. Similarly, Routing Parser 326 can receive Ci_Model 274 andHi_Model 276 and parse each model for information for downstreamoperators, Endpoint Checker 322 and Tenant Routing Checker 324.

After Ci_Model 274, Hi_Model 276, L_Model 270A and/or LR_Model 270B areparsed, Routing Policy Parser 320 and/or Routing Parser 326 can sendcleaned-up protocol buffers (Proto Buffs) to the downstream operators,Endpoint Checker 322 and Tenant Routing Checker 324. Endpoint Checker322 can then generate events related to Endpoint violations, such asduplicate IPs, APIPA, etc., and Tenant Routing Checker 324 can generateevents related to the deployment of BDs, VRFs, subnets, routing tableprefixes, etc.

FIG. 3C illustrates a schematic diagram of an example system for staticpolicy analysis in a network (e.g., Network Environment 100). StaticPolicy Analyzer 360 can perform assurance checks to detect configurationviolations, logical lint events, contradictory or conflicting policies,unused contracts, incomplete configurations, etc. Static Policy Analyzer360 can check the specification of the user's intent or intents inL_Model 270A to determine if any configurations in Controllers 116 areinconsistent with the specification of the user's intent or intents.

Static Policy Analyzer 360 can include one or more of the Operators 310executed or hosted in Assurance Appliance 300. However, in otherconfigurations, Static Policy Analyzer 360 can run one or more operatorsor engines that are separate from Operators 310 and/or AssuranceAppliance 300. For example, Static Policy Analyzer 360 can be a VM, acluster of VMs, or a collection of endpoints in a service functionchain.

Static Policy Analyzer 360 can receive as input L_Model 270A fromLogical Model Collection Process 366 and Rules 368 defined for eachfeature (e.g., object) in L_Model 270A. Rules 368 can be based onobjects, relationships, definitions, configurations, and any otherfeatures in MIM 200. Rules 368 can specify conditions, relationships,parameters, and/or any other information for identifying configurationviolations or issues.

Moreover, Rules 368 can include information for identifying syntacticviolations or issues. For example, Rules 368 can include one or morerules for performing syntactic checks. Syntactic checks can verify thatthe configuration of L_Model 270A is complete, and can help identifyconfigurations or rules that are not being used. Syntactic checks canalso verify that the configurations in the hierarchical MIM 200 arecomplete (have been defined) and identify any configurations that aredefined but not used. To illustrate, Rules 368 can specify that everytenant in L_Model 270A should have a context configured configured;every contract in L_Model 270A should specify a provider EPG and aconsumer EPG; every contract in L_Model 270A should specify a subject,filter, and/or port; etc.

Rules 368 can also include rules for performing semantic checks andidentifying semantic violations or issues. Semantic checks can checkconflicting rules or configurations. For example, Rule1 and Rule2 canhave aliasing issues, Rule1 can be more specific than Rule2 and therebycreate conflicts/issues, etc. Rules 368 can define conditions which mayresult in aliased rules, conflicting rules, etc. To illustrate, Rules368 can specify that an allow policy for a specific communicationbetween two objects can conflict with a deny policy for the samecommunication between two objects if the allow policy has a higherpriority than the deny policy, or a rule for an object renders anotherrule unnecessary.

Static Policy Analyzer 360 can apply Rules 368 to L_Model 270A to checkconfigurations in L_Model 270A and output Configuration Violation Events370 (e.g., alerts, logs, notifications, etc.) based on any issuesdetected. Configuration Violation Events 370 can include semantic orsemantic problems, such as incomplete configurations, conflictingconfigurations, aliased rules, unused configurations, errors, policyviolations, misconfigured objects, incomplete configurations, incorrectcontract scopes, improper object relationships, etc.

In some cases, Static Policy Analyzer 360 can iteratively traverse eachnode in a tree generated based on L_model 270A and/or MIM 200, and applyRules 368 at each node in the tree to determine if any nodes yield aviolation (e.g., incomplete configuration, improper configuration,unused configuration, etc.). Static Policy Analyzer 360 can outputConfiguration Violation Events 370 when it detects any violations.

FIG. 4 illustrates a flowchart for an example network assurance method.The method shown in FIG. 4 is provided by way of example, as there are avariety of ways to carry out the method. Additionally, while the examplemethod is illustrated with a particular order of blocks, those ofordinary skill in the art will appreciate that FIG. 4 and the blocksshown therein can be executed in any order and can include fewer or moreblocks than illustrated.

Each block shown in FIG. 4 represents one or more steps, processes,methods or routines in the method. For the sake of clarity andexplanation purposes, the blocks in FIG. 4 are described with referenceto Assurance Appliance 300, Models 270A-B, 272, 274, 276, and NetworkEnvironment 100, as shown in FIGS. 1A-B, 2D, and 3A.

At step 400, Assurance Appliance 300 can collect data and obtain modelsassociated with Network Environment 100. The models can include Models270A-B, 272, 274, 276. The data can include fabric data (e.g., topology,switch, interface policies, application policies, EPGs, etc.), networkconfigurations (e.g., BDs, VRFs, L2 Outs, L3 Outs, protocolconfigurations, etc.), security configurations (e.g., contracts,filters, etc.), service chaining configurations, routing configurations,and so forth. Other information collected or obtained can include, forexample, network data (e.g., RIB/FIB, VLAN, MAC, ISIS, DB, BGP, OSPF,ARP, VPC, LLDP, MTU, QoS, etc.), rules and tables (e.g., TCAM rules,ECMP tables, etc.), endpoint dynamics (e.g., EPM, COOP EP DB, etc.),statistics (e.g., TCAM rule hits, interface counters, bandwidth, etc.).

At step 402, Assurance Appliance 300 can analyze and model the receiveddata and models. For example, Assurance Appliance 300 can perform formalmodeling and analysis, which can involve determining equivalency betweenmodels, including configurations, policies, etc.

At step 404, Assurance Appliance 300 can generate one or more smartevents. Assurance Appliance 300 can generate smart events using deepobject hierarchy for detailed analysis, such as Tenants, switches, VRFs,rules, filters, routes, prefixes, ports, contracts, subjects, etc.

At step 406, Assurance Appliance 300 can visualize the smart events,analysis and/or models. Assurance Appliance 300 can display problems andalerts for analysis and debugging, in a user-friendly GUI.

Events generated in operation of a network environment can be clusteredinto event groups based on values of parameters of the networkenvironment defining the generated events. In clustering eventsgenerated in operation of the network environment, the events can bepresented to a network administrator according to event groups, therebyovercoming problems of a network administrator having to parse through alarge amount of events. This allows the network administrator to quicklyand efficiently characterize the network environment in order to providenetwork assurance despite the generation of a large number of events asnetwork environments increase in complexity and size.

A confidence score that values of parameters of a network environmentdefining events occurring in the environment are associated with aspecific event state can be identified. In characterizing events using asimple metric, e.g. the confidence score, a network administrator canquickly and efficiently diagnose problems in the network environmenteven as network environments increase in complexity and size.

FIG. 5 illustrates an example event clustering system 500. The eventclustering system 500 can cluster network events for purposes ofproviding network assurance. For example, the event clustering systemcan cluster network events and subsequently generate confidence scoresfrom the clustered network events for purposes of providing networkassurance.

The event clustering system 500 can be implemented at one or a pluralityof devices in a network environment. For example, the event clusteringsystem 500 can be implemented across one or a plurality of networkdevices, leafs, spines, controllers, and servers. In another example,the event cluster system 500 can be distributed across a plurality ofrouters in a network fabric.

The event clustering system 500 can be implemented through one or acombination of an appliance, application, and virtual machine. Forexample, the event clustering system 500 can be implemented as part ofthe assurance appliance 300.

The event clustering system 500 includes a network event sorter 502,event group storage 504, a network event analyzer 506, a network eventuser interface 508, and a minimum support event filter 510.

The network event sorter 502 can receive and sort network events.Network events can include events related to operation of a networkenvironment, such as the events described herein. For example, thenetwork event sorter 502 can receive a network event occurring within aspecific logical tenant space on a specific router indicating the routerhas failed a policy test. The network event sorter 502 can receive aplurality of network events generated at an epoch, e.g. each epoch of aconfigurable periodicity. Network events received by the network eventsorter 502 can be generated, collected, or otherwise identified by acontroller, application, or appliance, e.g. assurance appliance 300.

A network event can indicate an event state associated with the networkevent. An event state indicates a grade or subject associated with anetwork event. For example, an event state of a network event canindicate whether the network event is a passing event, a failing event,an informational event, or an error event.

Network events can be generated in response to checks performed in anetwork environment, e.g. at a configurable periodicity. For example, anetwork event can be generated in response to performing a policy checkon an EPG in a network environment. Additionally, network events can begenerated based on operation of a network environment. For example, anetwork event can indicate an error occurred during operation of anetwork environment within a specific logical location in a tenant spacein the network environment. A network event can include can include oneor a combination of values of parameters defining the network event, anevent state associated with the network event, a generated error orwarning, a log, and stimuli and circumstances that led to creation ofthe network event.

Network events and indicated event states can be associated with orotherwise classified by event categories. Event categories can bedefined according to characteristics of a network environment inoperation causing creation of corresponding network events. Examples ofevent categories include policy events, tenant routing events,configuration violation events, logical lint events, and forwardingevents. For example, if a failure event is created in response to abridge domain failing to adhere to a policy during a policy check, thenthe event can be classified as a failed policy event. In anotherexample, if a network device in a tenant logical space passes aforwarding or routing check, then the event can be characterized as apassing forwarding event.

Either or both event states and event categories can be indicated byspecific event codes associated with network events. For example, anetwork event can be associated with a failing event code indicating theevent is a failing event. In another example, a network event can beassociated with a passing forwarding event code indicating the event isa passing forwarding event, e.g. the event is created in response to apassed forwarding test and/or data is being forward through a logicalportion of a network environment.

A network event can be defined by values of parameters of a networkenvironment. Parameters of a network environment include parameters thatdefine characteristics of a network environment through creation andmaintenance of the network environment. For example, parameters of anetwork environment can include a model, e.g. a logical model, which canbe deployed into a network fabric forming a network environment.Specifically, parameters of a network environment can include parametersthat define a network environment on one or a combination of a networklayer, a logical layer, and a physical layer.

Parameters that define a network environment on a network layer caninclude network hierarchy parameters that form a hierarchy of networkparameters. Specifically, parameters of a network environment caninclude an identification of a tenant, e.g. in a network layer, a bridgedomain, and a virtual routing and forwarding instance. For example,values of parameters defining a network environment on a network layercan include a specific VRF of a specific tenant in which a network eventassociated with a forwarding failure occurs.

Parameters defining a network environment on a logical layer can includelogical hierarchy parameters that form a hierarchy of logicalparameters. Specifically, parameters of a network environment caninclude an identification of a tenant, e.g. in a local layer, anapplication profile, and an identification of an endpoint group. Forexample, values of parameters defining a network environment on alogical layer can include a specific application executing for aspecific endpoint group in which a network event associated with apolicy failure occurs.

Parameters defining a network environment on a physical layer caninclude physical hierarchy parameters that form a hierarchy of physicalparameters. Specifically, parameters of a network environment caninclude characteristics of a device, an identification of a networkdevice, and characteristics of a physical port. For example, values ofparameters defining a network environment on a physical layer caninclude a specific port used to transmit data about which a networkevent is created, and an indication of whether a physical device whichincludes the port is a spine router or a leaf router.

The network event sorter 502 can sort received network events into eventgroups. In sorting network events into event groups, the network eventsorter 502 can add a network event into one or a plurality of eventgroups. For example, the network event sorter 502 can sort a policyfailure event occurring in a specific EPG into an event group for policyfailures and also an event group for the specific EPG.

The network event sorter 502 can sort network events into event groupsbased on parameters of a network environment defining either or both thenetwork events and the event groups. For example, if a network eventoccurs in a specific bridge domain in a specific tenant logical space,then the network event sorter 502 can sort the network event into anevent group defined for the specific bridge domain in the specifictenant logical space. In another example, if a network event occurs at afirst port on a specific leaf router, then the network event sorter 502can sort the network event into an event group defined for the specificleaf router.

The network event sorter 502 can sort received network events into eventgroups based on event categories associated with the network events. Forexample, if a network event is a tenant routing event failure, then thenetwork event sorter 502 can sort the network event into an event groupincluding tenant routing events. Additionally, the network event sorter502 can sort received network events into event groups based on bothparameters of a network environment and event categories defining thenetwork events and event groups. For example, if a network event is apolicy failure event occurring at a specific EPG in a specific tenantspace, then the network event sorter 502 can sort the network event intoan event group including policy failures for the specific tenant.

Referring back to the event clustering system 500 shown in FIG. 5, theevent group storage 504 stores data indicating defined event groups andnetwork events sorted into the event groups by the network event sorter502. Specifically, the network event sorter 502 can update the eventgroup storage 504 to include defined event groups and network eventssorted into the event groups. For example, the network event sorter 502can update the event group storage 504 to indicate a created event groupfor network events occurring at a specific leaf router in a specifictenant space. Further in the example, the network event sorter 502 canupdate the event group storage 504 to include network events occurringat the specific leaf router in the tenant space that are sorted into theevent group.

The network event analyzer 506 can analyze events sorted by the networkevent sorter 502, potentially for purposes of providing networkassurance. Specifically, the network event analyzer 506 can analyzeevents sorted into one or a plurality of event groups by the networkevent sorter 502, as indicated by data stored in the event group storage504. For example, the network event analyzer 506 can analyze networkevents sorted into an event group defined for a specific applicationexecuting in a specific EPG of a tenant.

In analyzing network events, the network event analyzer 506 can identifyeither or both event states and event categories of the network events.For example, the network event analyzer 506 can identify a network eventis a tenant routing failure event. The network event analyzer 506 canidentify either or both event states and event categories of networkevents based upon event groups of the network events. For example, if anetwork event is sorted into an event group of failed policy events,then the network event analyzer 506 can determine the event is or isotherwise related to a failed policy event.

Additionally, in analyzing network events, the network event analyzer506 can identify values of parameters of a network environment definingthe network events. For example, the network event analyzer 506 canidentify a network event was generated in response to operation of a VRFin a specific tenant space. The network event analyzer 506 can identifyvalues of parameters of a network environment for network events basedon event groups of the network events. For example, if a network eventis sorted into an event group defined by a specific bridge domain and aspecific leaf router, then the network event analyzer 506 can determinethe event was created through operation of the specific leaf router inthe specific bridge domain.

The network event analyzer 506 can identify a confidence score that oneor a combination of values of parameters of a network environment isassociated with a specific event state. For example, the network eventanalyzer 506 can identify a confidence score indicating there is a 95%chance a port of a spine router is associated with a failing networkevent, e.g. a failing network event is generated through operation ofthe port. Further, the network event analyzer can identify a confidencescore that one or a combination of values of parameters of a networkenvironment is associated with a specific event state and an eventcategory. For example, the network event analyzer 506 can identify aconfidence score indicating there is a 92% chance an EPG is associatedwith a passing policy event.

A confidence score identified by the network event analyzer 506 canindicate a frequency at which network events defined by one or acombination of values of parameters of a network environment have eitheror both a specific event state and a specific event category. Thenetwork event analyzer 506 can use one or a combination of identifiedevent states of network events, identified event categories of networkevents, event groups of network events, and identified values ofparameters of a network environment defining network events to identifya confidence score. For example, the network event analyzer 506 canidentify there is a 99% chance a leaf router is associated with apassing forwarding event from network events sorted into an event groupfor the leaf router.

The network event analyzer 506 can present an analysis of sorted networkevents to a user, e.g. a network administrator, through the networkevent user interface 508. As part of presenting an analysis of sortednetwork events to a user through the network event user interface 508,the network event analyzer 506 can present one or a combination of anidentified confidence score, an event group of a network event, anidentification of one or a combination of parameters of a networkenvironment defining one or a plurality of network events, an eventstate of one or a plurality of network events, and an event category ofa network event. For example, the network event analyzer 506 can presentto a user that there is a 94% chance a specific application executing inan EPG is associated with a failed policy event. In presenting ananalysis of network events, e.g. an identified confidence score, to auser, the network event analyzer 506 can reduce or eliminate the burdenon the user of having to sort through thousands of network events inproviding network assurance.

The network event analyzer 506 can present an analysis of sorted networkevents based on received user input, e.g. input received through thenetwork event user interface 508. For example, the network eventanalyzer 506 can present a confidence score that a specific value of aparameter defining a network environment is associated with a failingevent. In response to presenting the confidence score to a user, and thenetwork event analyzer 506 can receive input requesting a breakdown ofthe confidence score into specific event categories of failing events.In response to the input, the network event analyzer 506 can presentconfidence scores that the value is associated with the specific eventcategories of failing events.

Additionally, the network event analyzer 506 can present an analysis ofsorted network events based on a determined confidence score.Specifically, the network event analyzer 506 can present one or acombination of a confidence score that a value of a parameter of anetwork environment is associated with a specific event state, anidentification of the value of the parameter, and an identification ofthe event state, if the confidence score is above a threshold score. Forexample, if a confidence score that a specific EPG is associated with afailing event, then the network event analyzer 506 can present theconfidence score indicating a percentage that the EPG is associated witha failing event.

Referring back to the event clustering system 500 shown in FIG. 5, theminimum support event filter 510 filters network events for purposes ofthe network event analyzer 506 analyzing the filtered network events.The minimum support event filter 510 can filter network events sortedinto event groups. For example, the minimum support event filter 510 canfilter events sorted into an event group defined to include networkevents occurring at a specific leaf router. The network event analyzer506 can analyze network events after the events are filtered by theminimum support event filter 510.

The minimum support event filter 510 can use a minimum support, e.g. avalue, to filter out network events. A minimum support can specify athreshold number of times a network event appears in a set of networkevents, network events with a specific event state appear in a set ofnetwork events, network events in a specific event category appear in aset of network events, and/or values of parameters defining networkevents appear in a set of network events in order to analyze the networkevent or network events. For example, a minimum support can specify onethousand events, and if only two events occurring in a specific bridgedomain appear in an epoch, then the minimum support event filter 510 canfilter out the events from a plurality of network events generatedduring the epoch. In filtering network events, the minimum support eventfilter 510 can identify whether network events, an event state ofnetwork events, an event category of network events, and values ofparameters defining network events meets the minimum support. A minimumsupport used by the minimum support event filter 510 can be set by auser. By using a minimum support to filter network events beforeanalyzing network events, computational resources are conserved.Further, using a minimum support to filter network events beforeanalyzing the events decreases or eliminates creation of unwanted oruseless data, data that can potentially confuse an administrator orwaste the administrator's time.

FIG. 6 illustrates a flowchart for an example network assurance analysismethod. The method shown in FIG. 6 is provided by way of example, asthere are a variety of ways to carry out the method. Additionally, whilethe example method is illustrated with a particular order of blocks,those of ordinary skill in the art will appreciate that FIG. 6 and theblocks shown therein can be executed in any order and can include feweror more blocks than illustrated.

Each block shown in FIG. 6 represents one or more steps, processes,methods or routines in the method. For the sake of clarity andexplanation purposes, the blocks in FIG. 6 are described with referenceto the event clustering system 500 shown in FIG. 5.

At step 600, the network event sorter 502 sorts received network eventsbased on values of parameters of a network environment defining thenetwork events. Network events can be received from and generated oridentified by one or a combination of a controller, application, orappliance, e.g. assurance appliance 300. Network events can also besorted at step 600 based on either or both an event state of the networkevents and event categories of the network events.

At step 602, the network event analyzer 506 identifies event states ofthe network events. Event groups the network events are sorted into canbe used to identify event states of the network events. For example, ifa network event is sorted into an event group of failing policy events,then the network event analyzer 506 can identify an event state of thenetwork event is a failing event.

At step 604, the network event analyzer 506 determines a confidencescore that at least one of the values of the parameters of the networkenvironment is associated with a specific event state of the identifiedevent states. A confidence score can be calculated by comparing a numberof events at a specific event state defined by the at least one of thevalues of the parameters of the network environment with a total numberof events defined by the at least one of the values of the parameters ofthe network environment.

At step 606, the network event analyzer 506 presents the confidencescore, an identification of the at least one of the values of theparameters of the network environment, and/or an identification of thespecific event state to a user through the network event user interface508. Using the confidence scores, an administrator can quickly diagnosea problem and/or a source of a problem in a network environment withouthaving to parse through a multitude of generated network environmentsfor the network environment in providing network assurance.Additionally, an event category of network events used to determine theconfidence score can be presented to a user through the network eventuser interface 508.

FIG. 7 illustrates a diagram of an example logical flow for determiningconfidence scores for parameter values defining network events. The flowincludes receiving a plurality of network events including a firstnetwork event 700, a second network event 702, a third network event704, and a fourth network event 706. The plurality of network events canbe identified by and received from one or a combination of a controller,application, or appliance, e.g. assurance appliance 300.

Each of the received plurality of network events is defined by values ofparameters defining a network environment including a tenant parameter708, an application profile parameter 710, and an EPG parameter 712.Specifically, the first network event 700 is defined for a first tenantT1, for a first application App1, in a first endpoint group EPG1. Thesecond network event 702 is defined for a second tenant T2, for thefirst application App1, in a second endpoint group EPG2. The thirdnetwork event 704 is defined for the first tenant T1, for a secondapplication App2, in the first endpoint group EPG1. The fourth networkevent 706 is defined for the first tenant T1, for the first applicationApp1, in the first endpoint group EPG1.

Additionally, each of the received plurality of network events includesan event state 714 and an event category 716. Specifically, the firstnetwork event 700 is a policy event having a failing event state. Thesecond network event 702 is a policy event having a passing event state.The third network event 704 is a policy event having a passing eventstate. The fourth network event 706 is a policy event having a failingevent state.

Each of the plurality of network events can be sorted into event groupsbased on one or a combination of the values of the parameters definingthe events 708, 710, and 712, the corresponding event states 714 of eachevent, and the corresponding event category 716 of each event. Forexample, the first network event 700, the third network event 704, andthe fourth network event 706 can be sorted into the same event groupbased on the events all occurring for the first tenant T1 in the sameendpoint group EPG1.

Next, a frequency that each value of the parameters defines a networkevent in the plurality of network events is determined, otherwisereferred to as the support of the values of the parameters in the set ofnetwork events. Specifically, T1 defines the first network event 700,the third network event 704, and the third network event 706, and doesnot define the second network event 702. As T1 defines three out of thefour network events in the set of network events, T1 has a support inthe set of network events of ¾. Using this technique, the support of theremaining values of the parameters is as follows: App1 ¾, EPG1 ¾, T2 ¼,App2 ¼, and EPG2 ¼.

A minimum support 718 can be set to exclude or otherwise filter out thevalues of parameters from calculations of confidence scores. Forexample, if the minimum support 718 is set at ½, which is greater thanthe support for parameter values T2, App2, and EPG2, then thoseparameter values are filtered out leaving T1, App1, and EPG1.

Finally, confidence scores 720 are determined for the remainingparameters values, T1, App1, and EPG1, which are not filtered out of theset of values of parameters based on the minimum support 718. The shownconfidence scores 720 are calculated for parameter value combinations722, however in certain embodiments, confidence scores can be calculatedfor each of the values of the parameters. Additionally, the shownconfidence scores 720 are calculated for a failing event state 714,however in certain embodiments confidence scores can be calculated fordifferent event states, e.g. a passing event.

In calculating the confidence scores 720, the parameter valuecombinations 722 are formed for the remaining values of the parameters.The parameter value combinations 722 include the combinations of thefirst tenant T1 and the first endpoint group EPG1, the first tenant T1and the first application App1, the first application App1 and the firstendpoint group EPG1, and the first tenant T1 the first endpoint groupEPG1 and the first application App1. Then, a confidence score for eachparameter value combination is calculated. The confidence score can be aratio of the number of times a parameter value combination defines afailing network event compared to a total number of network eventsdefined by the parameter value combination.

Specifically, in the shown example, the parameter value combination ofT1 and EPG1 define the first network event 700, the third network event704, and the fourth network event 706 for a total of three networkevents. Two of those network events are failing network events.Therefore, in the shown example, the confidence score is the ratio of2/3 or 0.67. In other words, in the shown example, there is a 67% chancethe combination of T1 and EPG1 define a failing network event.

Similarly, in the shown example, the confidence score of the eachparameter value combination of T1 and App1, App1 and EPG1, and T1 App1and EPG1 are all 1.0 as each network event defined by each of theseparameter value combinations is a failing network event. In other words,in the shown example, there is a 100% chance a network event defined byany one of these combinations is a failing network event.

The disclosure now turns to FIGS. 8 and 9, which illustrate examplenetwork devices and computing devices, such as switches, routers, loadbalancers, client devices, and so forth.

FIG. 8 illustrates an example network device 800 suitable for performingswitching, routing, load balancing, and other networking operations.Network device 800 includes a central processing unit (CPU) 804,interfaces 802, and a bus 810 (e.g., a PCI bus). When acting under thecontrol of appropriate software or firmware, the CPU 804 is responsiblefor executing packet management, error detection, and/or routingfunctions. The CPU 804 preferably accomplishes all these functions underthe control of software including an operating system and anyappropriate applications software. CPU 804 may include one or moreprocessors 808, such as a processor from the INTEL X86 family ofmicroprocessors. In some cases, processor 808 can be specially designedhardware for controlling the operations of network device 800. In somecases, a memory 806 (e.g., non-volatile RAM, ROM, etc.) also forms partof CPU 804. However, there are many different ways in which memory couldbe coupled to the system.

The interfaces 802 are typically provided as modular interface cards(sometimes referred to as “line cards”). Generally, they control thesending and receiving of data packets over the network and sometimessupport other peripherals used with the network device 800. Among theinterfaces that may be provided are Ethernet interfaces, frame relayinterfaces, cable interfaces, DSL interfaces, token ring interfaces, andthe like. In addition, various very high-speed interfaces may beprovided such as fast token ring interfaces, wireless interfaces,Ethernet interfaces, Gigabit Ethernet interfaces, ATM interfaces, HSSIinterfaces, POS interfaces, FDDI interfaces, WIFI interfaces, 3G/4G/5Gcellular interfaces, CAN BUS, LoRA, and the like. Generally, theseinterfaces may include ports appropriate for communication with theappropriate media. In some cases, they may also include an independentprocessor and, in some instances, volatile RAM. The independentprocessors may control such communications intensive tasks as packetswitching, media control, signal processing, crypto processing, andmanagement. By providing separate processors for the communicationsintensive tasks, these interfaces allow the master microprocessor 604 toefficiently perform routing computations, network diagnostics, securityfunctions, etc.

Although the system shown in FIG. 8 is one specific network device ofthe present invention, it is by no means the only network devicearchitecture on which the present invention can be implemented. Forexample, an architecture having a single processor that handlescommunications as well as routing computations, etc., is often used.Further, other types of interfaces and media could also be used with thenetwork device 800.

Regardless of the network device's configuration, it may employ one ormore memories or memory modules (including memory 806) configured tostore program instructions for the general-purpose network operationsand mechanisms for roaming, route optimization and routing functionsdescribed herein. The program instructions may control the operation ofan operating system and/or one or more applications, for example. Thememory or memories may also be configured to store tables such asmobility binding, registration, and association tables, etc. Memory 806could also hold various software containers and virtualized executionenvironments and data.

The network device 800 can also include an application-specificintegrated circuit (ASIC), which can be configured to perform routingand/or switching operations. The ASIC can communicate with othercomponents in the network device 800 via the bus 810, to exchange dataand signals and coordinate various types of operations by the networkdevice 800, such as routing, switching, and/or data storage operations,for example.

FIG. 9 illustrates a computing system architecture 900 wherein thecomponents of the system are in electrical communication with each otherusing a connection 905, such as a bus. Exemplary system 900 includes aprocessing unit (CPU or processor) 910 and a system connection 905 thatcouples various system components including the system memory 915, suchas read only memory (ROM) 920 and random access memory (RAM) 925, to theprocessor 910. The system 900 can include a cache of high-speed memoryconnected directly with, in close proximity to, or integrated as part ofthe processor 910. The system 900 can copy data from the memory 915and/or the storage device 930 to the cache 912 for quick access by theprocessor 910. In this way, the cache can provide a performance boostthat avoids processor 910 delays while waiting for data. These and othermodules can control or be configured to control the processor 910 toperform various actions. Other system memory 915 may be available foruse as well. The memory 915 can include multiple different types ofmemory with different performance characteristics. The processor 910 caninclude any general purpose processor and a hardware or softwareservice, such as service 1 932, service 2 934, and service 3 936 storedin storage device 930, configured to control the processor 910 as wellas a special-purpose processor where software instructions areincorporated into the actual processor design. The processor 910 may bea completely self-contained computing system, containing multiple coresor processors, a bus, memory controller, cache, etc. A multi-coreprocessor may be symmetric or asymmetric.

To enable user interaction with the computing device 900, an inputdevice 945 can represent any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, speech and so forth. An outputdevice 935 can also be one or more of a number of output mechanismsknown to those of skill in the art. In some instances, multimodalsystems can enable a user to provide multiple types of input tocommunicate with the computing device 900. The communications interface940 can generally govern and manage the user input and system output.There is no restriction on operating on any particular hardwarearrangement and therefore the basic features here may easily besubstituted for improved hardware or firmware arrangements as they aredeveloped.

Storage device 930 is a non-volatile memory and can be a hard disk orother types of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 925, read only memory (ROM) 920, andhybrids thereof.

The storage device 930 can include services 932, 934, 936 forcontrolling the processor 910. Other hardware or software modules arecontemplated. The storage device 930 can be connected to the systemconnection 905. In one aspect, a hardware module that performs aparticular function can include the software component stored in acomputer-readable medium in connection with the necessary hardwarecomponents, such as the processor 910, connection 905, output device935, and so forth, to carry out the function.

For clarity of explanation, in some instances the present technology maybe presented as including individual functional blocks includingfunctional blocks comprising devices, device components, steps orroutines in a method embodied in software, or combinations of hardwareand software.

In some embodiments the computer-readable storage devices, mediums, andmemories can include a cable or wireless signal containing a bit streamand the like. However, when mentioned, non-transitory computer-readablestorage media expressly exclude media such as energy, carrier signals,electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implementedusing computer-executable instructions that are stored or otherwiseavailable from computer readable media. Such instructions can comprise,for example, instructions and data which cause or otherwise configure ageneral purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware, orsource code. Examples of computer-readable media that may be used tostore instructions, information used, and/or information created duringmethods according to described examples include magnetic or opticaldisks, flash memory, USB devices provided with non-volatile memory,networked storage devices, and so on.

Devices implementing methods according to these disclosures can comprisehardware, firmware and/or software, and can take any of a variety ofform factors. Typical examples of such form factors include laptops,smart phones, small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are means for providing the functions described inthese disclosures.

Although a variety of examples and other information was used to explainaspects within the scope of the appended claims, no limitation of theclaims should be implied based on particular features or arrangements insuch examples, as one of ordinary skill would be able to use theseexamples to derive a wide variety of implementations. Further andalthough some subject matter may have been described in languagespecific to examples of structural features and/or method steps, it isto be understood that the subject matter defined in the appended claimsis not necessarily limited to these described features or acts. Forexample, such functionality can be distributed differently or performedin components other than those identified herein. Rather, the describedfeatures and steps are disclosed as examples of components of systemsand methods within the scope of the appended claims.

Claim language reciting “at least one of” refers to at least one of aset and indicates that one member of the set or multiple members of theset satisfy the claim. For example, claim language reciting “at leastone of A and B” means A, B, or A and B.

What is claimed is:
 1. A computer implemented method comprising: sortingnetwork events in a network environment into one or more event groupsbased on values of parameters of the network environment defining thenetwork events; identifying event states of the network events sortedinto the one or more event groups; identifying each value of theparameters of the network environment and each combination of the valuesof the parameters of the network environment that define a number ofevents of the network events greater than or equal to a minimum specificnumber of events; determining for each of the values of the parametersof the network environment and each of the combination of the values ofthe parameters of the network environment that was identified, aconfidence score for each value of the parameters of the networkenvironment and the each combination of the values of the parameters ofthe network environment that is associated with a specific event stateof the event states using the network events sorted into the one or moreevent groups and the identified event states of the network eventssorted into the one or more event groups; and presenting, to a user, forthe each value of the parameters of the network environment and the eachcombination of the values of the parameters of the network environment,the determined confidence score, and an identification of the specificevent state.
 2. The method of claim 1, wherein the confidence scoreindicates a frequency that a network event of the network events definedby the at least one of the values of the parameters of the networkenvironment has the specific event state.
 3. The method of claim 1,wherein the event states include whether a network event is a failingnetwork event or a passing network event in the network environment. 4.The method of claim 1, wherein the at least one of the values of theparameters of the network environment includes a combination of aplurality of the values of the parameters of the network environment. 5.The method of claim 1, wherein the parameters of the network environmentinclude at least one of a logical hierarchy parameter of the networkenvironment, a network hierarchy parameter of the network environment,and a physical hierarchy parameter of the network environment.
 6. Themethod of claim 1, wherein the network events in the network environmentare identified by a network assurance appliance.
 7. The method of claim1, wherein the confidence score indicates a frequency that a networkevent of the network events defined by the at least one of the values ofthe parameters of the network environment has the specific event stateand is associated with a specific event category.
 8. The method of claim1, wherein the at least one of the values of the parameters of thenetwork environment include at least one of an identification of atenant in a logical layer, an application profile, and an identificationof an endpoint group.
 9. The method of claim 1, wherein the at least oneof the values of the parameters of the network environment include atleast one of an identification of a tenant in a network layer, anidentification of a virtual routing and forwarding instance, and anidentification of a bridge domain.
 10. The method of claim 1, whereinthe at least one of the values of the parameters of the networkenvironment include at least one of a characteristic of a physicalnetwork device as either a leaf or a spine and an identification of atleast one physical port.
 11. A system comprising: one or moreprocessors; and at least one computer-readable storage medium havingstored therein instructions which, when executed by the one or moreprocessors, cause the one or more processors to perform operationscomprising: identifying event states of network events defined by valuesof parameters of a network environment; identifying each value of theparameters of the network environment and each combination of the valuesof the parameters of the network environment that define a number ofevents of the network events greater than or equal to a minimum specificnumber of events; determining for each of the values of the parametersof the network environment and each of the combination of the values ofthe parameters of the network environment that was identified, aconfidence score for each value of the parameters of the networkenvironment and the each combination of the values of the parameters ofthe network environment that is associated with a specific event stateof the event states using the network events and the identified eventstates of the network events; and presenting, to a user, for the eachvalue of the parameters of the network environment and the eachcombination of the values of the parameters of the network environment,the determined confidence score and an identification of the specificevent state.
 12. The system of claim 11, wherein the confidence scoreindicates a frequency that a network event of the network events definedby the at least one of the values of the parameters of the networkenvironment has the specific event state.
 13. The system of claim 11,wherein the event states include whether a network event is a failingnetwork event or a passing network event in the network environment. 14.The system of claim 11, wherein the at least one of the values of theparameters of the network environment includes a combination of aplurality of the values of the parameters of the network environment.15. The system of claim 11, wherein the parameters of the networkenvironment include at least one of a logical hierarchy parameter of thenetwork environment, a network hierarchy parameter of the networkenvironment, and a physical hierarchy parameter of the networkenvironment.
 16. A non-transitory computer-readable storage media havingstored therein instructions which, when executed by a processor, causethe processor to perform operations comprising: sorting network eventsin a network environment into one or more event groups based on valuesof parameters of the network environment defining the network events;identifying event states of the network events sorted into the one ormore event groups; identifying each value of the parameters of thenetwork environment and each combination of the values of the parametersof the network environment that define a number of events of the networkevents greater than or equal to a minimum specific number of events;determining for each of the values of the parameters of the networkenvironment and each of the combination of the values of the parametersof the network environment that was identified, a confidence score foreach value of the parameters of the network environment and the eachcombination of the values of the parameters of the network environmentthat is associated with a specific event state of the event states usingthe network events sorted into the one or more event groups and theidentified event states of the network events sorted into the one ormore event groups; and presenting, to a user, for the each value of theparameters of the network environment and the each combination of thevalues of the parameters of the network environment, the determinedconfidence score, and an identification of the specific event state. 17.The media of claim 16, wherein the confidence score indicates afrequency that a network event of the network events defined by the atleast one of the values of the parameters of the network environment hasthe specific event state.
 18. The media of claim 16, wherein the eventstates include whether a network event is a failing network event or apassing network event in the network environment.
 19. The media of claim16, wherein the at least one of the values of the parameters of thenetwork environment includes a combination of a plurality of the valuesof the parameters of the network environment.
 20. The media of claim 16,wherein the parameters of the network environment include at least oneof a logical hierarchy parameter of the network environment, a networkhierarchy parameter of the network environment, and a physical hierarchyparameter of the network environment.